Black Mold On Sweet Gum Firewood Stack?

by Jodi
(Matthews, NC)

Moldy Firewood Stack

Question

We recently had a sweet gum tree cut down in our backyard, and my husband saved the wood to burn outdoors in our firepit and chiminea. However it is growing black mold on most of the pieces (from being cut down in April), and has a very strong, sweet odor that you can smell from halfway across the yard.

The firewood stack is maybe 50 yards away from our house. We have a 2.5 year old and another baby on the way, I am concerned about the health implications of keeping this moldy firewood around.

The location it is stacked does remain in the shade for most of the day, would relocating it to a sunny spot and having something underneath it (pallets, etc) so it's not in contact with the ground help clear this mold up?

What other alternatives do we have to clear up the mold asap?

Answer

Jodi,

Thanks for your question about sweet gum firewood. A green sweet gum tree (one that's been recently cut down) contains a lot of water within the wood. This water not only makes the pieces of wood really heavy to move, but it also increases the odds of the firewood molding. Many people experience mold growth on sweet gum compared to other various firewood types.

In the future to decrease the chance of mold growth you should definitely stack the wood on pallets or another similar device to elevate it off the ground. Sweet gum has a tendency to rot quickly if it rests on wet ground. You should also split the rounds (large chucks of wood) into smaller pieces. By splitting the wood it exposes more surface area to the wind and sun, allowing it to dry faster.

Splitting sweet gum is not easy. In fact, many people will only attempt splitting sweet gum if they have a hydraulic wood splitter. A maul or splitting axe might not do the trick on larger pieces. Sweet gum has a sweet smell that some people describe as pleasant or even similar to yeast. The smell you detect is probably just the wood and not related to the mold.

By looking at the picture you provided I would guess the wood turned moldy because it was really wet to begin with (common for sweet gum) and it was stacked in a shady area in April. April is a wet month anyway so due to the wet spring environment the wood probably never had a chance to dry. Plus, April temperatures are warm enough to promote mold growth but it's not really hot enough to quickly dry out wet firewood.

Having children myself I understand your concerns about black mold growing near your family. Now that the mold has already grown, there isn't anything I would recommend for removing or killing the existing mold. I don't recommend spraying a chemical like bleach on the wood because it could become airborne when you burn the wood in your fire pit or chiminea.

A lot of people burn moldy firewood in a wood stove or outdoor wood furnace and never have any issues because the smoke goes outside. Sitting around a campfire in the smoke is a different situation.

If you have concerns about the wood I would just give it away or try to sell it since the mold has already established itself. I know you probably don't want to loose the wood, but peace of mind is generally more important than a little firewood.

In the future you might want to split the wood, stack it in a sunny location and elevate it off the ground to help reduce the chance of mold growing. I think your mold is just a combination of a wet spring, warm temperatures, lack of sunlight and sweet gum, a wet wood to begin with.